The present invention relates to flexible flail trimmers for trimming and edging grass and cutting weeds and other vegetation. More particularly, the invention is directed to an apparatus guiding such trimmers during the edging operation, stabilizing the flail as it rotates, and protecting the operator from thrown debris during the trimming operation.
The invention presents certain improvements over the flexible flail trimmer and combined guide and guard disclosed in my previous patent, U.S. Pat. No. 5,115,870 (hereinafter the '870 patent), which was issued on May 26, 1992. U.S. Pat. No. 5,115,870 is fully and expressly incorporated by reference herein.
The '870 patent discloses a flexible flail trimmer having a rotatable guide and guard mounted inboard of a rotating cutting head and having indexing means for guiding the apparatus in both horizontal and vertical directions. In one embodiment, the combined guide and guard takes the form of a truncated cone and in another embodiment the combined guide and guard is a truncated hemisphere. In both embodiments, the combined guide and guard includes a circumferential lip extending radially outwardly from the base of the truncated cone or hemisphere. The lip extends outwardly in a plane parallel to the plane of the rotating flail. The outboard lip surface in effect provides a bearing surface against which the flail bears during rotation. The end of the flail extends radially beyond the edge of the lip as the flail rotates to provide the desired cutting action.
Among the advantages of the trimmer disclosed in the '870 patent is the ability to use the trimmer with the guide and guard oriented either vertically during edging operations or horizontally during conventional trimming operations. While using the trimmer in an edging operation, the user may orient the axis of rotation of the cutting head generally parallel to a lawn surface by rolling the junction between the circumferential lip and the base of the guide and guard along a sidewalk corner formed by its vertical edge and horizontal top surface. This juncture of the guide and guard effectively provides a means for indexing the trimmer both vertically and horizontally along a sidewalk edge such that the trimmer follows the sidewalk edge at a uniform vertical depth and horizontal distance to produce a neatly trimmed lawn edge.
Another advantage realized from the '870 device is that the circumferential lip of the combined guide and guard stabilizes undesirable wobble in the flail along substantially the entire length of the flail. In other trimmers in which flail wobble is not stabilized, the wobble tends to cause the spinning flail to produce rough, uneven cutting during both edging operations and conventional trimming operations. The '870 device, however, helps to produce more even cutting in conventional trimming operations. Also, since the flail tip retains a small amount of wobble, the flail tip clears a path which is wider that the diameter of the flail to provide a leading groove in the soil in which the lip rides during an edging operation.
Further advantages of the trimmer and guide/guard of the '870 patent include the ability to use one piece of equipment to perform two different lawncare operations, namely, trimming and edging. As a result, the total time taken to trim and edge a lawn is significantly reduced through the use of this single device. Also, the guide and guard provides the user protection from thrown debris during either trimming or edging operations. Finally, less debris is thrown and soil excavated during the edging operation therefore speeding the operation, reducing clean-up time, and necessitating less horsepower than conventional bladed edgers.
While the '870 patent discloses a trimmer and guide/guard having the many advantages cited above, the present invention contemplates certain improvements thereon related to trimming accuracy, flail stabilization and improved protection from thrown debris. In this regard, although the junction between the base of the guide/guard and the lip may be effectively used as an indexing means during an edging operation as described above, care must be taken by the operator not to allow the guide/guard to descend along the edge of the sidewalk so as to dig too deeply into the soil and/or produce a cut which strays from the edge of the sidewalk. This is especially true of the truncated cone embodiment of the '870 patent in which the straight, upper surface of the guide/guard may tend to slide down against the corner of the sidewalk unless the operator carefully maintains the outboard surface of the circumferential lip against the edge of the sidewalk.
In addition, the '870 patent does not present a way to protect the operator from debris thrown rearwardly from the cutting head. In this regard, the rotating nature of that guide/guard prevents a conventionally shaped rear guard from being attached to the guide/guard to protect the user.
Moreover, although the wobble produced at the end of the flail outside of the circumferential lip tends to advantageously form a leading groove in the soil during an edging operation, it may also serve to prevent an ideal, clean cut from being made during a conventional trimming operation where the guide/guard is oriented horizontally. For example, while using the trimmer horizontally on a lawn, the wobble at the end of the flail will tend to cause an uneven or rough cut along the top surface of the lawn.
Of course, the wobble of the flail in a conventional trimmer is much greater, and therefore produces a much less desirable cut, than that produced by the trimmer disclosed in the '870 patent. This is due to the circumferential lip of the guide/guard of the '870 patent which acts as a bearing surface for the rotating flail and thereby stabilizes the flail along almost the entire length of the flail. Therefore, past conventional trimmers suffer from the disadvantage of having relatively large amounts of wobble in the rotating flail while the trimmer disclosed in the '870 patent still retains a small amount of wobble in the rotating flail in the tip portion of the flail extending radially outwardly from the periphery of the guide/guard.
Accordingly, it has been one objective of the present invention to provide an improved indexing means to positively limit the vertical movement of the guide/guard during an edging operation and allow an operator to more easily keep the trimmer against the edge of the sidewalk and cut at a uniform depth during the edging operation.
A further object of the invention has been to provide a trimmer having a guide/guard which is convertible from a rotatable design used in edging operations to a nonrotatable design having a rear guard for protecting the operator during trimming operations in which the guide/guard is used in a generally horizontal orientation.
A still further object of the invention has been to produce an improved apparatus for stabilizing a flexible flail of a trimmer to provide cleaner, more even cuts when trimming.